Fused grading shield



Sept? 1933- K. A. HAWLEY 1,926,871

FUSED GRADING SHIELD Filed Dec. 23, 1929 2 Sheets-Sheet 1 L Jnvenkw 2Ken? 14. HQdi// Straw/Yum Sept. 12, 1933. HAwLEY 1,926,871

FUSED GRADING SHIELD Filed Dec. 23, 1929 2 Sheets-Sheet 2 QCIEI PatentedSept. 1 2, 1933 PATENT OFFICE 1,926,871 FUSED GRADING SHIELD Kent A.Hawley, Baltimore, M(l., assignor to Locke Insulator Corporation,Baltimore, Md., a corporation of Maryland Application December 23, 1929Serial No. 416,115

5 Claims.

The invention relates to protective devices for use in connection withhigh tension transmission lines for the purpose of protecting strings ofinsulators against damage resulting from arcing or flashing over oflightning impulses such as may occur during thunderstorms.

It is well known that numerous patents have been granted covering theemployment of electrodes of one sort or another at the ends of a stringor chain of insulators used to suspend a conductor from a groundedsupport. Very frequently these electrodes take the form of horns at thetop of the-string and either horns or a ring at the lower end of thestring. Certain modifications and adaptations of the principle involvedhave also been provided in conjunction with installations wherein theconductor is mounted above a grounded support by means of pin, post orpedestal type insulators which are well known in the art. It has alsobeen proposed to provide means in the nature of a fire extinguishingmaterial for extinguishing the arc, or an explosive ignited upon theoccurrence of an are for diverting the same from the insulators so thatit will not continue for a sufficient length of time to cause anydamage. However, known devices for this purpose are comparatively crudeand possess numerous disadvantages, some of which are a mere matter ofmounting or mechanical construction and another of which is that thereis insufficient means to take care of a succession of flash-overs.

It is with the above facts in view that I have devised the presentinvention which has for its general object the improvement of devices ofthis class and which has for an important object the provision of anarrangement wherein there is a plurality of fuses, preferably of themechanical expulsion type, adapted to come into play one at a time or insequence at different times so that protection will be afforded againstmore than a single flash-over.

A more specific object of the invention is to provide a protectivedevice embodying a sectional grading ring in which each section isequipped with a fuse.

A still further objectis' to provide a protective device embodying anovel means for supporting the fuses from the grading ring, thearrangement being moreover such that burned out or exhausted fuses maybe readily replaced by new ones.

Another specific object is to provide a protective apparatus which has asingle point suspension with respect to the string of insulators andwhich may therefore. be very readily installed without providing amultiplicity of attachment devices.

An additional object is to provide a device of this character which willbe simple and inexpensive to make, easy to use, positive in action,efficient and durable in service, and a general improvement in the art.

To the attainment of the foregoing and other objects and advantages, theinvention preferably consists in the details of construction and thearrangement and combination of parts to be hereinafter more fullydescribed and claimed, and Llustrated in the accompanying drawings inwhich:

Figure 1 is a side elevation of a string of suspension insulatorsequipped with my invention and showing one form thereof,

Figure 2 is a section taken on the line 2-2 of Figure 1,

Figure 3 is a side elevation showing a grading ring at the lower end oftheinsulator string provided with a plurality of fuses, and

Figure 4 is a top plan view thereof.

Referring more particularly to the drawings the letter A designates astring of suspension insu- $0 lators of any ordinary or preferred typeconnected by any of the usual means for the purpose. At the upper end ofthe string is a suspension element B by means of which it may besuspended from a tower or other support, and the string is intended tocarry, at its lower end, a suspension element C to which is connected aclamp D supporting the conductor E. At the upper end of the string is anarcing horn device F of any ordinary or preferred type.

In carrying out the form of the invention disclosed in Figures 1 and 2,I provide a grading ring 10 which is here shown as carried by insulators11 mounted on arms 12 of angular form which have their inner endssecured to a suspension member 13 interposed between the lowermostinsulator unit and the suspension element C for the clamp D. The member13 necessarily conforms to the type of connection with which theinsulator units are equipped, it being well known that some are of theclevis type whereas others are adapted to be connected together instring or chain formation by ball and socket members.

Each insulator 11 is provided at itsupper end with an angle bracket 14bolted at 15 to the grading ring and fastened by a bolt 16 to a metallicinsert 17 embedded and secured within the insulator. At their lower endsthe insulators are secured to the arms 12 by bolts 18 screwed intoinserts 19 anchored Within the insulators. By this arrangement it willbe seen that the grading ring is insulated with respect to the clamp andconductor.

The protective means in this instance comprises a fuse 20 which has oneend electrically connected with the grading ring 10 and its other end inelectrical connection with the conductor through the elements C, 13, 12and 18. The fuse may be of any ordinary construction suitable for thepurpose but is preferably of the expulsion type well known in the art.Details are not given here as they are rather immaterial to the presentinvention. However, a fuse of this type does include an outer member ofinsulating material within which are metallic elements connected withterminal ferrules 21. To mount this fuse so that it will functionproperly I provide angular brackets 22 one of which is mounted at thelower end of one insulator and the other at the upper end of the other,these brackets being held by the bolts 18 and 16 respectively. Springclips 23 are mounted on these angular brackets and the metal ferrules ofthe fuse are snappingly engageable therein and held by spring tension.It will be noted that when the fuse is in applied position it extendsdiagonally and that its upper or active end will, upon the occurrence ofan arc, divert the same away from the string.

In the operation it will be seen that as the fuse is in series betweenthe conductor and the air gap between the grading ring and the arcinghorns F when a flash-over occurs as the result of a suddensurge alongthe line, this excess current will not only jump the gap but must flowthrough the fuse, melting away the fusible element forming a partthereof as disclosed in said co-pending application. In fuses of thistype the internal parts are thrown out by spring pressure and the arcacross the gap will consequently be diverted and extinguished.

In Figures 3 and 4 I have illustrated a modification which possessesadvantages over what has been described above. Referring to theseflgures in detail, I have provided a grading ring formed of two similarsections 10 between the ends of which are interposed and mounted in anysuitable manner insulators 24. The sections of the ring are bolted toangle brackets 25 secured in any desired manner, such as that abovedescribed, to the upper ends of the insulators 11 which have their lowerends secured to the arms 12 as described in connection with the firstform of the invention. Each bracket 25 is here shown as carrying a clip26. Secured at the lower ends of the insulators are brackets 27corresponding to the brackets 22 and equipped with clips 28. In thisinstance, as I provide two ring sections I make use of two of the fuses20 which have their terminal ferrules 21 engaged within the oppositeclips 28 and 26 respectively. By this arrangement it is apparent thatthe fuses are diagonally disposed or inclined with respect to v thevertical and also with respect to each other.

each fuse having one end in electrical connection with the conductor andthe other in electrical connection with the grading ring so as to be inseries with the air gap between the ring and arcing horns. In this formthe operation is exactly the same as that of the first described form,the only difference being that as there are two fuses there is ampleprotection against two flash-overs as only one fuse will be blown at onetime.

From the foregoing description and a study of the drawings it will beapparent that I have thus provided a simply constructed and inexpensivearrangement for protecting insulator strings against damage in the eventof flash-over, and consequently avoiding service interruption. After anelectrical storm or other unusual condition which might result inflash-overs, it is a simple matter for an inspection crew to ascertainwhat fuses have been blown and to replace those that have been so thateverything will be all set in preparation for a future emergency. It isbelieved that the construction, operation and advantages will be readilyapparent to one skilled in the art without further explanation.

While I have shown and described the preferred embodiment of theinvention, it should be understood that the disclosure is merely anexemplification of the principles involved as the right is reserved tomake all such changes in the details of construction as will widen thefield of utility and increase the adaptability of the device providedsuch changes constitute no departure from the spirit of the invention orthe scope of the claims hereunto appended.

Having thus described the invention, I claim:

1. A protective device for a string of suspension insulators carried bya grounded support and carrying a conductor, comprising arcing horns atthe upper end of the string, a grading ring at the lower end of thestring, arms at the lower end of the string and in electrical connectionwith the conductor, insulators mounted upon said arms and supportingsaid grading ring, and a fuse carried by said insulators and having oneend in electrical connection with the conductor through one of said armsand having its other end in electrical connection with the ring to be inseries with the gap between the ground and the conductor.

2. A protective device for a string of suspension insulators suspendedfrom a grounded sup- 115 port and carrying a conductor, comprising anelectrode at the upper end of the string connected with the ground, agrading ring at the lower end of the string, metallic arms at the lowerend of the string, insulators mounted on said arms and carrying saidgrading ring, and a fuse having one end mounted at the bottom of oneinsulator and its other end mounted at the top of the other insulator,said fuse constituting the sole electrical connection between the con-125 ductor and the ring and being in series with the air gap between thering and the electrode.

3. A protective device for a string of suspension insulators, theinsulators depending from a grounded support andcarrying a conductor,180 comprising arcing horns at the upper end of the string, a gradingring at the lower end of the string formed of sections with insulatorsinterposed therebetween, means for supporting said sections andinsulating the same from the conductor, and a plurality of fuseselectrically connected at one end with the conductor and electricallyconnected at their other ends with the respective ring sections, saidfuses being in series with the air gap between the respective ringsections and the arcing horns.

4. A protective device for a string of suspension insulators carried bya grounded support and carrying a metallic conductor support, comprising an electrode at the upper end of the string, supporting membersat the lower end of the string in electrical connection with theconductor, insulators mounted upon said last named supporting members,an electrode carried 150 by said second named insulators and located atioo by said metallic element, insulators mounted on said support, agrading ring surrounding the string and mounted upon said insulators,clips at the upper and lower ends of said last named insulators, andexpulsion fuses having terminal ferrules engaged within said clips, saidfuses being in electrical connection at one end with the conductor andat the other end with the grading ring and being in series with the gapbetween the arcing horns and the conductor.

IGINT A. HAWLEY.

